1 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s 2 3 // An explicitly-defaulted function may be declared constexpr only if it would 4 // have been implicitly declared as constexpr. 5 struct S1 { 6 constexpr S1() = default; // expected-error {{defaulted definition of default constructor is not constexpr}} 7 constexpr S1(const S1&) = default; 8 constexpr S1(S1&&) = default; 9 constexpr S1 &operator=(const S1&) = default; // expected-error {{explicitly-defaulted copy assignment operator may not have}} 10 constexpr S1 &operator=(S1&&) = default; // expected-error {{explicitly-defaulted move assignment operator may not have}} 11 constexpr ~S1() = default; // expected-error {{destructor cannot be marked constexpr}} 12 int n; 13 }; 14 struct NoCopyMove { 15 constexpr NoCopyMove() {} 16 NoCopyMove(const NoCopyMove&); 17 NoCopyMove(NoCopyMove&&); 18 }; 19 struct S2 { 20 constexpr S2() = default; 21 constexpr S2(const S2&) = default; // expected-error {{defaulted definition of copy constructor is not constexpr}} 22 constexpr S2(S2&&) = default; // expected-error {{defaulted definition of move constructor is not constexpr}} 23 NoCopyMove ncm; 24 }; 25 26 // If a function is explicitly defaulted on its first declaration 27 // -- it is implicitly considered to be constexpr if the implicit declaration 28 // would be 29 struct S3 { 30 S3() = default; // expected-note {{here}} 31 S3(const S3&) = default; 32 S3(S3&&) = default; 33 constexpr S3(int n) : n(n) {} 34 int n; 35 }; 36 constexpr S3 s3a = S3(0); 37 constexpr S3 s3b = s3a; 38 constexpr S3 s3c = S3(); 39 constexpr S3 s3d; // expected-error {{constant expression}} expected-note {{non-constexpr constructor}} 40 41 struct S4 { 42 S4() = default; 43 S4(const S4&) = default; // expected-note {{here}} 44 S4(S4&&) = default; // expected-note {{here}} 45 NoCopyMove ncm; 46 }; 47 constexpr S4 s4a; // ok 48 constexpr S4 s4b = S4(); // expected-error {{constant expression}} expected-note {{non-constexpr constructor}} 49 constexpr S4 s4c = s4a; // expected-error {{constant expression}} expected-note {{non-constexpr constructor}} 50 51 struct S5 { 52 constexpr S5(); 53 int n = 1, m = n + 3; 54 }; 55 constexpr S5::S5() = default; 56 static_assert(S5().m == 4, ""); 57
